Human scenario recognition systems have attracted attention because of their applications in healthcare, intelligent controls, smart houses, etc. The scenario understanding can be achieved by using the information of locations and motions of the subjects. Generally scenario recognition is different from motion recognition. Motion recognition focuses on the individual's motions, while scenario recognition is more concerned about the context such as the size of the group, locations and postures of human subjects, and the like. The identification of such information for motion recognition does not require very accurate motion capture because the idea is to extract systematic, intrinsic patterns of the motion signals instead of analyzing each action snapshot. In scenario understanding, the targets can be measured at a distance despite the subject's cosmetic conditions. The system can use low-resolution sensory data for accurate context identification, and it can be used for non-cooperative subjects under examination, i.e., the system can be non-intrusive since the subject may be unaware of the deployed sensors nearby.
Regarding human scenario recognition, the video camera is perhaps the most widely used device. However, it consumes large communication bandwidth and storage space, and it can be easily influenced by the illumination and background conditions. For example, it cannot accurately capture the subject that is in dark environment or is hidden behind other objects.
Pyroelectric Infrared (PIR) sensors have been employed for human detection, tracking and identification due to their low cost, tiny hardware, and operation stability under varying temperatures. Existing systems employ a passive PIR sensor that uses dual elements to form a differential measurement, so that it can detect the thermal change of the environment (rather than the absolute temperature). This configuration enables it to detect the moving thermal source, but also limits its application for static targets.
In daily lives, many ordinary scenarios involve static humans. During the process of indoor scenario perception, one or several human subjects may not generate any detectable motions within a certain period. For example, people are sitting for a talk or reading books. Therefore, what is desired are systems, methods and devices that overcome challenges in the art, some of which are described above. In particular, systems, methods and devices that provide thermal detection of static and moving objects are desired.